For the umpteenth time, likely mayoral candidate Bill Thompson has been ordered to pay the city nearly $600,000 in fines dating to his 2009 run for mayor.

Thompson refuses.

The Department of Sanitation first levied $594,375 in fines after Thompson illegally plastered thousands of campaign posters on public property in 2009. Appeals have failed, and now it’s time to write a check.

We’re reviewing the options, says a flack. But there’s only one: Thompson owes $600,000. He needs to pay up.

By refusing, he risks putting himself in the same league as his ethically challenged successor, City Comptroller John Liu, who has refused to pay his own $527,400 fine for the past three years — even as he presumes to sit in judgment over the city’s books.